# Drawing lines from 2 or more separate points to one target point and calculating the distance between them

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Vance Blake on 23 Aug 2019
Commented: Vance Blake on 1 Sep 2019
Hello, I have a plot where I create random points scattered around a set of central points. I am trying to draw lines from the 2 central points to another target point,. There will be more central points than 2 in the future so an adaptable solution is preferred. After drawing the lines, I need to calculate the distance between each point and the target point, find the minimum distance value and keep the line associated with the minimum distance value and delete the longer one. Below Ive included a picture of the basic situation. I line A is longer than line B then I will keep line B and vice versa. I need to be able to do this for every point on the graph and hopefully simultaneously. I also included the test code I am using to draw lines between one central point and one target but I havent been able to tweak it properly for multiple points.
for i = 1:LengthB
x2(i) = B(i,1);
y2(i) = B(i,2);
Line_matrix1(i,:) = line([x0, x2(i)],[y0, y2(i)], 'linewidth', 1.5, 'color', 'r');
drawnow;
hold on
end
darova on 23 Aug 2019

Adam Danz on 23 Aug 2019
Edited: Adam Danz on 23 Aug 2019
Use pdist2() to compute the distance between point p and points q. Compute the minimum distance and then plot that line (no need to plot all lines to find the distances).
% define point p and points [q]
p = [2,3]; %[x,y]
q = [7,3; %[x,y]
5,4;
1,5];
% Compute distance between point p and points [q]
dist = pdist2(p,q);
% Find shortest distance; minDistIdx will be the row number in q
[minDist, minDistIdx] = min(dist);
% Plot shortest line
plot([p(1),q(minDistIdx,1)], [p(2),q(minDistIdx,2)])
Vance Blake on 1 Sep 2019